The present invention relates to braking systems for heavy vehicles, such as trucks, buses, and tractor-trailer combinations. More particularly, the invention relates to an emergency brake system for stopping a vehicle in the event of failure of the vehicle's normal service brake system. The emergency brake system is independent of the service brake system, but may be used in conjunction with the vehicle's service brake system in an emergency to decrease the distance required to stop the vehicle and to avoid jack-knifing. The emergency brake system may also be used as a security device to prevent unauthorized movement of the vehicle.
The service brake system of a heavy vehicle, such as a truck, bus, or tractor-trailer combination, may fail for a variety of reasons. For example, failure of the hydraulic or air system that provides power for the brake system prevents activation of the vehicle's brakes. When traveling downhill, a vehicle's brakes may overheat, causing the brakes' friction material to glaze, thereby rendering the brakes useless.
When a heavy vehicle's brakes fail, it may be impossible to avoid an accident, resulting in property damage and serious personal injuries or death.
When the driver of a tractor-trailer combination attempts an emergency stop, especially on a slippery road surface, the tractor and trailer may jackknife. That is, the trailer may skid laterally relative to the tractor.
A large majority of modern trailers do not have external frames. Most prior art emergency brake systems transfer emergency braking force to the external frame of the vehicle. If such a prior art emergency brake system were installed on most modern trailers, the emergency braking force would subject the trailer to undesirable stress and possible damage.